Method for spray drying coffee whitener

ABSTRACT

Method and apparatus are provided for manufacture of dry particulate food products. In the method, particles of a fluid edible dispersion are provided in the drying chamber of the spray dryer. Circulating air is introduced into the chamber. The circulating air is of a quantity, temperature and humidity sufficient to dry the particles. A fraction of the dried particles is entrained in the circulating air and is subsequently separated to provide a first fraction of particles having a relatively high bulk density. A second fraction of particles is removed from the chamber by gravity and is simultaneously conveyed and cooled to provide a product having relatively low bulk density and rapid sinkability and solubility.

United States Patent 1 1 Nezbed et al.

[111 3,738,412 June 12, 1973 METHOD FOR SPRAY DRYING COFFEE 2,627,4632/1953 Meade 99/199 X WHITENER 2,977,317 3/1961 Rodis et a1 3,072,4861/1963 Oakes et al..... Inventors: Robert Nezbed, Highland Park;3,514,300 5/1970 Mishkin et a] 99/199 William H. Zamzow, Glenview, bothof Primary ExaminerNorman Yudkoff 73 Assi n I K a 0 Cor N Y k, AssistantExaminerJ. Sofer 1 g ee R: c po 8 I cw or Attorney-Anderson, Luedeka,Fitch, Even and Tabin [22] Filed: Sept. 8, 1970 57 ABSTRACT [21] Appl.No.: 70,030 Method and apparatus are provided for manufacture of dryparticulate food products. In the. method, particles of a fluid edibledispersion are provided in the drying [52] US. Cl. 159/48 R, 99/199chamber of the Spray dryen Circulating air is intro [51] Int. Cl. B0ld1/16, B0ld l/OO, F26b 3/12 duced mto the chamber. The c1rculat1ng air 1sof a [58] Field of Search 159/48, 4 MS, 4 UM,

59/4 0 99/199 200 203 quantlty, temperature and hum1d1ty sufficient todry the particles. A fraction of the dried particles is entrained in thecirculating air and is subsequently sepa- [56] References Clted rated toprovide a first fraction of particles having a rel- UNITED STATESPATENTS atively high bulk density. A second fraction of particles3,143,428 8/1964 Reimers et al..... 99/141 is removed from the chamberby gravity and is simulta- 3,547,179 12/1970 l-lussman 159/4 CC neouslyconveyed and cooled to provide a product hav- 1'157935 10/1915 Gray159/48 R X ing relatively low bulk density and rapid sinkability and2,148,355 2/1939 .lakosky et al. 159/48 R X solubilit 2,324,526 7/1943Morganthaler 99/71 2,413,420 12/1946 Stephanoff 34/10 3 Claims, 1Drawing Figure i 41 in 39 mxsa- ,I. 27 13K o as PASTEURIZEFL -/-37 31HOMOGENIZER\ ee :21: 43 v nu'za V $1 I 59 In ovsnsizz i 7.3 INES 13SIFTER iPRoD AIR 5 67 i PRODUCT 1 METHOD FOR SPRAY DRYING COFFEEWHITENER The present invention is generally directed to an improvedmethod and apparatus for preparing dried food products. Moreparticularly, the present invention is directed to a method andapparatus for preparing dried food products by spray drying which have arelatively lower bulk density than has been heretofore available byspray drying.

Many dried fatty emulsion products have been formulated from non-dairyingredients for use in whitening coffee and other hot beverages. Suchdried fatty emulsion products have been commonly referred to as coffeewhiteners." Coffee whiteners usually contain an edible vegetable oranimal fat or oil, water soluble sugar solids, a water dispersibleprotein and emulsifying agents. Coffee whitener formulations must becapable of dispersing completely in a hot liquid such as coffee, with nofeathering or free fat appearing on the surface. The coffee whitenermust be capable of whitening coffee to an extent comparable to dairycream, while at the same time contributing a pleasing taste and flavorto the finished drink. A further requirement for household use, however,is that the coffee whitener have good sinking characteristics and becapable of sinking beneath the surface of the hot liquid within arelatively short time. Sinking characteristics are dependent upon bulkdensity and particle size, and it is desirable to produce coffeewhitener having a relatively low bulk density and a relatively largeparticle size for household use. Coffee whiteners intended for vendingmachine use may have a higher bulk density due to the manner in whichthe coffee whitener is added to the dispensing cup during a vendingsequence. That is, in the prepara: tion of a hot liquid from a vendingmachine, the coffee whitener-is administered to the bottom of the cupalong with a beverage powder before the hot liquid is added to the cup.Therefore, a good sinking characteristics and low bulk density are notso important for coffee whitener to be used in vending operations.

Relatively large particle size and relatively low bulk density are alsodesirable when producing dried skim milk and other milk products byspray drying. It has been the general practice in the milk industry totreat spray dried skim milk or whole milk so as to agglomerate the spraydried particles so as to provide a product with a relatively largerparticle size. The agglomerated product is more readily dispersible inwater to provide a reconstituted milk product. It would be desirable toprovide a method and apparatus for spray drying milk products so as toprovide a dry milk product with a relatively larger particle size and arelatively lower bulk density than has heretofore been possible withoutpost spray drying treatment.

It would also be desirable to provide a method and apparatus for themanufacture of coffee whitener wherein a coffee whitener product may beprovided with the desired level of bulk density and with rapidsinkability. It would also be desirable to provide a method andapparatus whereby coffee whitener may be provided having bulk densitythat is suitable both for vending machines and for household use. Itwould also be desirable to provide a method and apparatus for themanufacture of coffee whitener wherein a coffee whitener product may beprovided which has a low bulk density while at the same time providing acoffee whit- -ener product with a higher bulk density. As used herein,the term bulk density refers to the weight of a unit volume of materialand is expressed in units of grams per cc.

Accordingly, it is a principal object of the present invention toprovide an improved method and apparatus for the manufacture of dryparticulate food products. It is another object of the present inventionto provide an improved method and apparatus for the manufacture of foodproducts by spray drying whereby a product may be obtained with adesired bulk density and particle size. It is a further object of thepresent invention to provide an improved method and apparatus for themanufacture of fluid food products whereby a first product may beproduced with a relatively high bulk density and a second productproduced simultaneously with a relatively low bulk density.

These and other objects of the present invention will become moreapparent from the following detailed description and accompanyingdrawing which is a schematic flow sheet of apparatus useful in thepresent in vention.

Various features of the present invention will be hereinafterparticularly described with respect to spray drying a particular fluidfood product, e.g., coffee whitener. It should be understood, however,that the method and apparatus of the invention are equally suitable formanufacturing a variety of food products where a larger particle size orlower bulk density is desired. The method and apparatus of the inventionare particularly suitable for drying fluid dairy products, such as skimmilk, whole milk and whey.

In accordance with various features of the present invention, a liquidcoffee whitener emulsion comprising a suitable fat or oil, a watersoluble sugar, a water dispersible protein and an emulsifying agent isspray dried in apparatus so as to simultaneously provide a first driedcoffee whitener product having a relatively small particle size and arelatively high bulk density, and a second coffee whitener producthaving a relatively large particle size and a relatively low bulkdensity. In the method, particles of the fluid coffee whitener emulsionare provided in the drying chamber of the vertical spray dryer.Circulating air is introduced into the chamber and the particles aredried within the chamber. Tl-le circulating air is removed from thechamber and an entrained fraction of dried particles of coffee whitenerare removed by the circulating air. The entrained fraction of driedparticles are separated from the drying air to provide a first coffeewhitener product having a relatively small particle size and arelatively high bulk density. A second fraction of dried coffee whitenerparticles are removed by gravity from the drying chamber. The secondfraction is treated by simultaneously conveying and cooling theparticles to provide a second coffee whitener product having arelatively large particle size and a relatively low bulk density.

Now looking particularly at the drawing, the apparatus of the inventionis set forth in a schematic flow sheet. The apparatus comprises a spraydrying system 11, a first product collection system 13, and a secondproduct collection system 15.

The spray drying system consists of a preparation tank 17, mixer 19,pasteurizer 20, homogenizer 21, hold tank 22, pump 23 and spray nozzle24. The spray drying system also includes drying chamber 25, blower 27and heater 29. After a fluid coffee whitener emulsion is prepared in thepreparation tank 17, the coffee whitener formulation is pasteurized,homogenized and transferred to the holding tank 22. The coffee whitenerformulation is then pumped by means of pump 23 to the spray nozzle 24which injects particles of fluid coffee whitener emulsion into the spraychamber 25. The blower 27 provides circulating air in the drying chamber25 for drying the particles, and the air is heated by the heater 29prior to being introduced into the drying chamber 25.

The first product collection system 13 consists of air duct 31 whichconnects to a first cyclone 33. The product is removed from the airentering the cyclone 33. The air exits from cyclone 33 through duct 35,and dried product which is removed from the air exits from the cyclonethrough automatic valve 43. Duct 35 connects to a second cyclone 37.Additional dried product is removed from the air in cyclone 37 and theair exits through duct 39. The air is moved through the first cyclone 33and the second cyclone 37 by means of blower 41. The dried productremoved from the second cyclone 37 exits from the cyclone throughautomatic dump valve 44 and into product collection duct 45.

The product from the first cyclone and the second cyclone is movedthrough the product collection duct 45 by means of blower 47. A filter48 may be provided at the entrance to duct 45 to remove any impuritiesfrom incoming air. The product collection duct 45 leads to a thirdcyclone 49. Air exits from the third cyclone 49 through duct 51 and isrecycled to duct 31. The product is removed from the third cyclone 49through automatic dump valve 53. The product is then passed throughsifter 55 so as to remove oversized lumps of product which may have beenformed by agglomeration. The oversized product exits from the sifter atoutlet 57, while the finished product exits at outlet 59. The principalproduct may then be collected and packaged into suitable containers (notshown).

The second product collection system consists of a conveyor 61 andsifter 63. The conveyor 61 is provided with cooling means (not shown)which may consist of any suitable cooling apparatus. Cooling may beeffected by passing cool air through the conveyor or providing theconveyor with cooling coils so as to cool the product by convection orconduction. The second product is removed from the bottom of the dryingchamber by gravity into conveyor 61.

The dried coffee whitener product which exits from conveyor 61 is passedthrough sifter 63 to remove oversize particles. In this connection, thedried product is substantially less than 16 mesh, and sifter 63 is usedfor the purpose of removing a relatively few large agglomeratedparticles. For this reason, sifters 55 and 63 are provided with screenshaving a mesh size of about 16 or higher. The oversize product isremoved from sifter 63 through outlet 65, while the product is removedthrough outlet 67.

In operation of the present invention, a coffee whitener emulsion isfirst prepared in the preparation tank 17. Various coffee whitenerformulations are known in the art, and such various formulations are notparticularly described herein except in the example which follows below.Any of the various coffee whitener formulations may be used in thepractice of the present invention. As previously indicated, a coffeewhitener formulation includes a vegetable or animal fat or oil, a waterdispersible sugar, a water dispersible protein and emulsifying agents.

The coffee whitener formulation is agitated in the preparation tank 17by the mixer 19 and is thereafter pasteurized, homogenized andtransferred to holding tank 22. The coffee whitener formulation which isnow an emulsion is then transferred by pump 28 to the spray nozzle 24.Generally, the pump 23 is capable of providing the coffee whiteneremulsion to the nozzle 24 at pressures of from about 1,000 psi to about5,000 psi. Heated air is introduced into the drying chamber of the spraydryer by the blower 27. The air is heated by heater 29 before beingintroduced into the drying chamber 25. The heated air acts to dryparticles of the fluid coffee whitener emulsion which are introducedinto the chamber 25 by the nozzle 24. The air and the dried particlesprogress downwardly through the chamber 25. The air is removed throughduct 31 and carries with it entrained particles of dried coffeewhitener. Other particles of coffee whitener continue down- Wardly inthe chamber 25 by the action of gravity. The particles which movedownwardly to the bottom of the chamber 25 are removed from the chamberby gravity into the conveyor 61.

The relative proportions of dried coffee whitener particles which areentrained by the circulating air and which continue downwardly throughthe chamber 25 are controlled by the pressure within the chamber 25. Ingeneral, as the pressure within the chamber 25 is reduced belowatmospheric, a higher proportion of dried particles of coffee whitenerwill be entrained by the circulating air which exits through duct 31. Asthe pressure is increased within the chamber 25, a higher proportion ofparticles of coffee whitener will fall to the bottom of the chamber andbe removed by gravity through line 65 containing an automatic valve. Asa pressure of from about 0.1 to about 0.25 inches of water vacuum, anapproximately equal proportion of the dried particles will be entrainedby the circulating air and pass downwardly by gravity to the conveyor61. Other proportions of high bulk density product to low bulk densityproduct may be obtained by adjusting the pressure within the range ofabout atmospheric pressure to about 2 inches of water vacuum. It is notgenerally desirable to establish a pressure within the chamber 25 whichis positive with respect to atmospheric pressure. When the pressurewithin the chamber 25 is positive, there is a tendency to blow driedparticles of coffee whitener from the spray drying system into theatmosphere. If higher proportions of low bulk density product aredesired, all or part of the dried product having a relatively high bulkdensity may be reintroduced as a dry powder into chamber 25 as shown bythe I dotted line 70. The dry powder may be transferred and blown intothe chamber 25 by any suitable means.

The entrained particles of dried coffee whitener which are removed fromthe chamber 25 through duct 31 by the exiting circulating air areremoved from the circulating drying air by the cyclones 33 and 37. Thecoffee whitener product, which is removed by the cyclones, istransferred through automatic valves 43 and 44 to duct 45, where thedried particles are conveyed by air to the final product removal cyclone49. The product removed by cyclone 49 is transferred through automaticvalve 53 to sifter 55. Oversize particles are removed by sifter 55through outlet 57. The finished product is removed through outlet 59 andmay be then packaged into suitable containers.

The product obtained from the sifter 55 has a bulk density within therange of from about 0.60 to about 0.70 grams per cc. The bulk density isdetermined by placing a known weight of the product in a container andpacking the product by vibration until the volume is constant. Theproduct obtained from the sifter 5 is suitable for use in vendingmachines, but does not have particularly good properties with respect tosinking when placed on top ofa hot liquid beverage. While not wishing tobe bound by any theory, it is believed that the relatively smallparticle size product with relatively high bulk density is the result ofair conveying of the product through duct 45. It is believed that airconveying of the dried particles of coffee whitener removed fromcyclones 33 and 37 results in abrasion of the particles and reduction inparticle size.

The second fraction of coffee whitener particles are removed from thebottom of the chamber 25 by gravity into conveyor 61. The driedparticles are conveyed by conveyor 61 and are simultaneously cooled. Itis important that the dried particles being conveyed by conveyor 61 bekept in slight relative motion with respect to each other so thatsubstantial agglomeration does not occur during the conveying step. Apreferred method of conveying the dried particles is by means ofvibratory conveyors. Other suitable means for conveying the particles isby means of fluidized bed conveyors or by relatively low velocity airconveying. Air conveying is suitable for conveying the particles so longas the particles are not subjected to any substantial rapid change indirection while the particles are being conveyed.

Cooling of the particles during conveying is required to preventsubstantial agglomeration of the particles during conveying and toreduce the temperature of the particles to a level where any substantialdeterioration of the product by heat effects does not occur. Cooling maybe effected by passing air over the particles within the conveyor 61.Cooling may also be effected by surrounding the conveyor with coolingcoils and cooling the particles through convection or conduction. Othersuitable means for effecting cooling of the particles during conveyingwithin conveyor 61 will be readily apparent to one skilled in the art.

Cooling is sufficient to reduce the product temperature by at least F asthe product is being conveyed. Preferably cooling is sufficient toreduce the product temperature by from about 30F to about 120F. In thisconnection, the outlet temperature of the circulating air is desirablymaintained within the range of from. about l90F to about 2l0F. If theoutlet air temperature is above about 2l0F the product may be harmed byburning. lfthe outlet air temperature is below about l90F the moisturelevel of the product is too high and substantial sticking of the productto the walls of the chamber occurs. When the above indicated range foroutlet air temperature is maintained, the product temperature as itexits from the chamber by gravity is from about l75F to about 185F.

The coffee whitener product obtained by gravity from the bottom of thechamber 25 has a relatively large particle size and a relatively lowbulk density. in this connection, a comparison of the particle size ofthe coffee whitener products obtained from sifter 63 and sifter 55 ispresented below. The product obtained from sifter 63 is designated lowdensity, while the product obtained from sifter 55 is designated as highdensity.

The above tabulation of relative particle sizes of the low densityproduct obtained by gravity from the chamher and the high densityproduct obtained from entrained product carried by the air leaving thechamber is intended to be representative only. Absolute measurement ofparticle sizes of dried coffee whitener particles is extremely difficultin that the particles tend to break upon being forced through thescreen. Therefore, the above comparison is intended to be repreaentativeand relative only, and is not intended to be an absolute measure of theparticle size distribution of the two coffee whitener fractions obtainedby the method of the present invention.

The low density product obtained by gravity from the bottom of chamber25 generally has a bulk density of from about 0.40 to about 0.55 gramsper cc., the bulk density being measured as previously described. Thelow density coffee whitener product has extremely good sinking anddispersion characteristics when the product is added to the top of a hotfluid beverage. In general, the product sinks beneath the surface of thehot fluid beverage within a time period of about 10 seconds. This isconsidered an acceptable sinking time for a coffee whitener product tobe used in the household.

The following example further illustrates various features of thepresent invention, but is not intended to limit the scope of theinvention, which is defined in the appended claims.

EXAMPLE A coffee whitener formulation is prepared which has thefollowing ingredients at the indicated levels:

Ingredient Weight Lbs. Coconut Fat (92) 2,020 Emulsifier 240 Corn syrupsolids (24 DE) 3,200 Sodium caseinate 220 Salts Water 2,500

The above ingredients are added to the preparation tank 17 and areagitated by mixer 19 and homogenized so as to provide an emulsion. Theemulsion is then transferred to spray nozzle 24 by pump 23 at a pressureof 4,000 psi. The emulsion is sprayed into chamber 25 at a rate of 6gallons per minute. Air, which has been heated to a temperature of 335Fis then introduced into chamber 25 at a rate of 25,500 cubic feet perminute. The pressure within the chamber 25 is adjusted by means of adraft control at the outlet of blower 41. The outlet air temperature is198F.

The air, after passing through chamber 25, exits from chamber 25 throughduct 31. About half of the dried particles of coffee whitener areentrained in the air which exits through duct 31. The dry particles ofcoffee whitener which are removed from the chamber by means of the airexiting through duct 31 are removed from the air by means of cyclones33, 37 and 49. A product is obtained from cyclone 49 which has a bulkdensity of 0.65 grams per cc. The total coffee whitener product obtainedfrom cyclone 49 represents 48.3 percent by weight (dry basis) of theweight of the starting materials.

A second product is removed by gravity from the bottom of chamber 25.The product is transferred by means of a vibratory conveyor 61 whilecool air is passed over the surface of the dried coffee whitener onconveyor 61. The product exits from the chamber 25 at a temperature of90F while being conveyed by conveyor 61. The coffee whitener product isremoved from conveyor 61 and passes to sifter 63. A coffee whitenerproduct is obtained from sifter 63 which has a bulk density of 0.49grams per cc. The coffee whitener product obtained from sifter 63represents 51.2 percent by weight (dry basis) of the starting drymaterials. THe sinking time of the low bulk density product in hotcoffee is 7 seconds and no particles were left on the surface of thecoffee. The sinking time of the high bulk density product in hot coffeeis seconds and there is a residual scum of particles remaining on thesurface.

The method and apparatus of the present invention provide a means fordrying a coffee whitener formulation so as to obtain a fraction of theformulation having a relatively high bulk density and a second fractionof the formulation having a relatively low bulk density. The proportionsof the two fractions produced may be adjusted as desired. The low bulkdensity product is not readily provided by direct spray drying withconventional spray drying apparatus. It has heretofore been considerednecessary to include an agglomeration step in order to obtain a coffeewhitener formulation and other dairy products having a bulk density aslow as that provided by the method of the invention.

What is claimed is:

l. A method for drying liquid coffee whitener so as to simultaneouslyprovide a first product having a relatively high bulk density and asecond product having a relatively low bulk density and good sinkingcharacteristics, comprising providing particles of a liquid coffeewhitener dispersion in the drying chamber of a spray dryer, introducingcirculating air into said chamber, said air being ofa quantity,temperature and humidity sufficient to dry said particles and provide anoutlet air temperature in the range of from about F to about 210F,entraining a fraction of said dried particles in said circulating airand removing said circulating air containing a first fraction ofparticles from said drying chamber, separating said first fraction ofparticles having a relatively high bulk density of from about 0.60 toabout 0.70 grams per cc from said circulating air, removing from saiddrying chamber a second fraction of coffee whitener particles having abulk density of from about 0.40 to about 0.55 grams per cc by gravityand simultaneously cooling while conveying only said second fraction toprovide a packageable product having relatively low bulk density andrapid sinkability and solubility, said conveying being effected byvibratory conveying so that said dried particles of said second fractionare maintained in slight relative motion in respect to each other andsaid cooling during said conveying being sufficient to reduce thetemperature of said second fraction by at least about 20F.

2. A method in accordance with claim 1 wherein at least a part of saidfirst fraction of dried particles is recycled to said drying chamber asdried particles.

3. A method in accordance with claim 1 wherein said drying chamber ismaintained at a pressure of from about atmospheric to about 2 inches ofwater vacuum during said drying.

1. A method for drying liquid coffee whitener so as to simultaneouslyprovide a first product having a relatively high bulk density and asecond product having a relatively low bulk density and good sinkingcharacteristics, comprising providing particles of a liquid coffeewhitener dispersion in the drying chamber of a spray dryer, introducingcirculating air into said chamber, said air being of a quantity,temperature and humidity sufficient to dry said particles and provide anoutlet air temperature in the range of from about 190*F to about 210*F,entraining a fraction of said dried particles in said circulating airand removing said circulating air containing a first fraction ofparticles from said drying chamber, separating said first fraction ofparticles having a relatively high bulk density of from about 0.60 toabout 0.70 grams per cc from said circulating air, removing from saiddrying chamber a second fraction of coffee whitener particles having abulk density of from about 0.40 to about 0.55 grams per cc by gravityand simultaneously cooling while conveying only said second fraction toprovide a packageable product having relatively low bulk density andrapid sinkability and solubility, said conveying being effected byvibratory conveying so that said dried particles of said second fractionare maintained in slight relative motion in respect to each other andsaid cooling during said conveying being sufficient to reduce thetemperature of said second fraction by at least about 20*F.
 2. A methodin accordance with claim 1 wherein at least a part of said firstfraction of dried particles is recycled to said drying chamber as driedparticles.
 3. A method in accordance with claim 1 wherein said dryingchamber is maintained at a pressure of from about atmospheric to about 2inches of water vacuum during said drying.